Electromagnetic (EM) forces play the major part in many modern technologies. Motors, magnetohydrodynamic (MHD) seals, electromagnetic pumps, levitators, electrical bearings, and springs are some of the modern technologies in which EM forces play a leading role. In some applications, EM forces can reach tremendous values. For example, thanks to a capability to develop incredibly large electromagnetic forces, electric guns or launchers can fire materials to higher velocities than are achievable by rockets or chemical/powder guns. In the majority of induction heating applications, coil current also can reach appreciable values. For example, currents of 10 kA and higher are not unusual for many induction heat treating applications, including shaft hardening and gear hardening High currents produce significant forces that have a pronounced effect on coil life. Without proper consideration, those forces can physically move the heated workpiece or flux concentrator, and even bend the induction coil or fixture, which may negatively affect overall system reliability and repeatability, as well as dramatically reduce coil life.
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